Body Composition Measurements and Nutritional Status in Children with Clinical Conditions: Cystic Fibrosis and Cancer

Murphy, Alexia (2010). Body Composition Measurements and Nutritional Status in Children with Clinical Conditions: Cystic Fibrosis and CancerPhD Thesis, School of Medicine, The University of Queensland.

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Abstract Malnutrition, as indicated by body composition measurements, is a common problem in many paediatric diseases and is an issue of considerable concern. Optimal body composition is vital in children with clinical conditions because body composition will ultimately affect prognosis. In order to manage nutritional problems, it needs to be understood what body composition changes occur in children in response to clinical conditions and how body composition can be validly measured in paediatric clinical populations. This thesis investigated the body composition of children between five and 18 years of age from three different populations; healthy, diagnosed with cystic fibrosis or diagnosed with cancer. This research aimed to formulate the Body Cell Mass Index for use in children, report on the suitability of body composition methods for use in paediatric cystic fibrosis and cancer populations and detail the body composition of children with cystic fibrosis and cancer. This research showed that the Body Cell Mass Index for interpreting total body potassium measurements in children is BCM/HT2.5 for females and BCM/HT3 for males. Section Two on the validity of body composition assessment methods found that air displacement plethysmography can be used in cystic fibrosis populations to determine body composition, but that currently available bioelectrical impedance analysis equations should not be used to determine fat free mass in children with cystic fibrosis. In the cancer population, it was found that the recommended methods of weight and height indices, arm anthropometry and albumin measurements do not accurately determine nutritional status. Section three of the thesis examined the nutritional status of children with cystic fibrosis and cancer. It was found that while the children with cystic fibrosis were well nourished despite their condition, that children being treated for cancer were malnourished with low levels of body cell mass and high levels of fat mass. The determination of the Body Cell Mass Index in this thesis has changed and improved the way body cell mass results are reported for children assessed in the Body Composition Laboratory, Royal Children’s Hospital. The methodology findings will lead to better identification of nutritional problems in children with cystic fibrosis and cancer, with clinical centres adopting appropriate body composition techniques in these populations. The reporting of the nutritional status of children with cystic fibrosis and cancer will ensure that clinicians understand the impact that these conditions have on nutritional status and will allow them to tailor nutritional interventions to combat the potential changes that may result in each condition.